1. Field of Invention
The invention relates to a light emitting diode (LED) package and process of making the same, and in particular to a light emitting diode package that uses silicon-on-insulator as a substrate and process of making the same.
2. Related Art
Conventional SMD LED (Surface mount device LED) packages include two types: A lead frame type and a circuit board type. The lead frame type uses a metal frame and a heat resistance plastic to inject molding for forming a base, which is used to fix an LED chip. The circuit board type uses a composite circuit board as a substrate and then continues the steps of chip fixing, wire bonding and sealing. The two types both have disadvantages, such as low heat resistance, which result in the defects of the SMD LED, especially when the bonding of the SMD LED and other circuit boards requires high-temperature furnace processes (about 250˜300° C.). Another disadvantage is poor heat dispersal. Heat accumulates during the operation of the LED, especially for a high power LED. The rising temperature affects the light emitting efficiency and the quality of the LED. In addition, it is difficult to make a reflective cavity in the conventional SMD LED process while scaling it down.
The prior art provides a process of packaging LEDs. As shown in FIG. 1, it uses a silicon substrate as the package substrate. The front surface of the silicon substrate 8 has spectacular crystallizing direction for etching a cavity, and the back surface of the silicon substrate is used for forming a through hole electrode 13. After an insulation layer 15, reflective layer 16 and electrode layers 17 and 18 are formed, a base is formed for disposing the LED chip 3. The LED process is completed after the processes of chip fixing, wire bonding, sealing and cutting. This technique has the advantages of good heat resistance, ease in manufacturing the reflective cavity, and good heat dispersal so that the conventional process of packaging the SMD LED is improved. However the technique requires multiple furnace processes for growing the insulation layer, which complicate the technique. Thus, there is a need for an easier process of packaging an LED, which improves heat resistance and heat removal properties, and also solves the problem of manufacturing the reflective cavity.